Camshaft adjusters are known from the prior art and are used in internal combustion engines, for example in passenger cars, trucks or other land-bound vehicles. However, they may also be deployed in other air-bound or water-bound vehicles which use internal combustion engines.
A device for changing the control times of gas exchange valves in an internal combustion engine is thus known from DE 10339871 A1. This publication relates to a device for changing the control times of gas exchange valves of an internal combustion engine, which is situated on the input end of a cam supported in the cylinder head of an internal combustion engine and which includes a drive unit which is in driving connection with a crankshaft and is axially delimited by two side covers as well as a drive unit which is rotatably fixedly connected to a camshaft and inserted into the drive unit. The output unit has an axial through-bore for a central fastening screw, while the drive unit has a central axial bore in the side cover facing away from the camshaft, through which the fastening screw is guided into the through-bore in the output unit. The axial bore may be closed pressure medium-tight with the aid of a screw plug provided with a sealant, which has a screw head suitably designed for engaging a tool and a hollow cylindrical screw shaft. The screw plug is designed as a one-piece light-weight integral part made of a thermoplastic plastic material for the axial bore in the side cover of the drive unit and its sealant, a fiberglass-reinforced polyamide being used as the plastic.
Stator cover units for camshaft adjusters are known from the publications DE 10 2010 008 004 A1 and DE 10 2010 008 005 A1, an integral design including a stator and a locking cover being selected on the one hand, and a two-part design including a locking cover and a stator being selected on the other hand. In this case, the stator unit includes an integral cover, i.e., one that is connected thereto as a single piece.
Stator cover units of this type have become common components in the meantime, and are used in newer internal combustion engines of motor vehicles. They are part of a camshaft adjuster as described above and are thus used to actuate the camshaft or the cams mounted on the camshaft. Due to the cams of the camshaft, which is set into rotation by a crankshaft, gas exchange valves in an internal combustion engine may be actuated thereby. The control times of the gas exchange valves may be purposefully defined with the aid of the configuration and shape of the cams. An adjustment of the valve opening times via the camshaft adjuster permits an increase in efficiency of the internal combustion engine, which is felt, in particular, as performance gain and fuel savings. For this reason, additional improvements are strived for again and again in camshaft adjusters or the individual components of a camshaft adjuster.
A camshaft adjuster usually includes a stator, a locking cover, a rotor positioned in the stator as well as a sealing cover. In the installed state, the stator is rotatably fixedly connected to a crankshaft, while the rotor is rotatably fixedly connected to a camshaft. The stator is usually designed to have at least one vane abutment surface, against which the vanes of a rotor abut in the installed state. On the whole, a targeted rotation of the camshaft with respect to the stator within a predetermined angle range is made possible by the use of a camshaft adjuster. The phase angle of the camshaft with respect to the crankshaft may thus be changed within certain limits.
To be able to maintain the stator and rotor in an optimum position, in particular during startup or idling of an engine, a sliding block is introduced within the locking cover. The sliding block is used for the rotatably fixed locking of a rotor, a piston engaging with the sliding block so that the stator cover unit is mechanically connected to a rotor in a form-fitting manner. As a result, high forces act upon the sliding block in the locked state.
However, the disadvantage of known stator cover units, for example in a unit known from U.S. Pat. No. 6,311,654 B1, is their relatively high manufacturing and assembly complexity.
Due to the installation space restrictions and customer specifications with regard to a driving plane, such as a belt plane, the fact that the locking cover is unable to be clamped and rotated in the circumferential direction directly via the gripper used occurs over and over again. This problem increases in a locking cover situated axially within an offset mounted part. A greater assembly complexity is required and, in the worst case, the desired adjuster concept may not even be implemented due to an imprecise assembly, since the locking cover is situated axially within another component, for example a belt pulley stator unit. Assembly is made even more difficult if a restoring spring must be pretensioned with the locking cover.